Built-up Columns MCQ with answer and solution

Concept

Maximum slenderness ratio of lacing bars

Formula

NONE

Step-by-step solution

1. Lacing bars are used to connect components of built-up compression members. 2. As per IS 800, the maximum slenderness ratio of lacing bars shall not exceed 145. 3. This limit ensures stability and prevents premature buckling of the lacing elements. Answer: B

Explanation

Lacing bars in built-up columns are designed to hold the main components together and resist lateral forces. According to standard design codes, the slenderness ratio of a lacing bar must not exceed 145 to prevent premature buckling of the lacing itself. This ensures that the built-up column acts as a single integrated structural unit.

Why the other options are wrong

A) 180 is the maximum slenderness ratio for compression members under dead and live loads. C) 200 is the limit for tension members. D) 140 is lower than the IS code allowable limit of 145 for lacing bars.

Shortcut

Lacing maximum slenderness ratio is capped at 145 (remember "Lacing = 145").

Common mistake

Confusing the maximum slenderness ratio for lacing bars (145) with general compression members (180).